Pet diets, particularly dog and cat food diets, strive to be highly nutritional. In doing so these diets, both dry and wet, utilize nutritionally appropriate materials in the proper balance. However, these materials often differ from the natural diet of carnivorous mammals such as dogs and cats. Generally the meat content of these pet foods, particularly in dry diets, is no more than about 25 to 30 wt % of the diet. Diets having more meat are potentially advantageous due to such parameters as appearance, palatability and overall acceptability to the pet. However, such meat quantities are not normally found in pet diets because the standard method of manufacturing these diets, extrusions followed by cutting into chunks and/or particles with standard knife blades, cannot prepare a diet with substantially higher meat content, for example, a meat content minimum of about 40 or 45 wt % of the composition. Although not wishing to be bound by this theory, it is thought that the higher water content accompanying the higher meat content makes the diet difficult to form in the extruder as well as essentially noncuttable at an economically attractive rate by the standard knives post extruder.
It has now been discovered that the problems can be seriously ameliorated or solved by adding cellulose or cellulose-like material to the diet. The presence of this material(s) permits standard extrusion and cutting apparatus to manufacture a diet having a minimum of about 40 to 45 wt % meat content. This discovery is particularly advantageous since it eliminates the necessity of having expensive meat chunk forming and processing equipment available for processing. Additionally, it also adds a nutritious material to the diet as well.
In accordance with the invention, there is a pet diet composition comprising at least about 40 wt % meat with cellulosic material in quantities effective to allow extrusion and cutting of the composition post extruder, the composition having the said meat wt % minimum in the extruder.
A further aspect of the composition is a process for producing a pet diet composition having at least about 40 wt % meat which comprises extruding and post extrusion cutting the composition having the said wt % meat minimum wherein the composition has cellulosic material in quantities sufficient to allow effective extrusion and post extrusion cutting of the composition.
The usual method of making pet foods, particularly for dogs and cats, is generally well-known. For dry diets, components are combined in a preconditioner and then fed into an extruder where they are mixed, heated (cooked) and expanded. The extrudate is then emitted from the extruder and cut using standard knife blades, into the proper sized particles for packaging. These diet components include meat, grain, carbohydrate, various adjuvants such as vitamins and minerals, as well as moisture and the like. Wet diets are prepared in the same manner and the meaty xe2x80x9cchunkxe2x80x9d that is chunk or slice which is a discrete meaty particle which is added to a liquid gravy for packaging is prepared in the extruder and sliced or further treated to obtain the desired size prior to mixing with the gravy.
Meat is meant to include any proteinaceous material obtained from an animal source. Meat includes beef, pork, lamb, fish, chicken, turkey, veal, and the like and mixtures thereof. In accordance with the teaching of this invention, meat can now be at least about 40 wt % of the dry pet diet composition, particularly that for dogs and cats. Desirably it can be more than about 45 or 50 wt %. The upper limit of meat in the dry diet depends upon the nutritional needs met by the components of the diet as well as the quantity of cellulosic materials present in the diet, the palatability of the diet and the processability of the diet as well as the diet cost. Generally quantities above about 65 wt % are not employed, desirably about 60, 55 or 50 wt % can be a maximum. When used in a wet diet, the meat in the xe2x80x9cchunkxe2x80x9d itself is at least about 40, 45 or 50 wt % of the chunk with 65, 60, 55 or 50 wt % of the xe2x80x9cchunkxe2x80x9d being the maximum.
The cellulosic fibrous component used in the diet is cellulose fiber and other plant fibers or fibrous microbial polysaccharides. Examples of such latter materials include hemicellulose, lignins and other pectic substances found naturally in the supporting structure of seed-bearing plants. The particle size of these materials can be those as normally manufactured that is in the powder form or larger. Although they can be smaller, these particles generally have minimum particle sizes of at least about 5 microns, desirably at least about 10 microns and more desirably at least about 20 microns. The maximum size is that which can be reasonably processed and bring about the processability of the increased meat in the diet composition. Generally a particle size of about 5000 microns need not be exceeded, desirably about 2000 or 1000 microns need not be exceeded. The quantity of cellulosic fiber content is an amount sufficient to bring about extrudability of a formed composition and cutting of that composition post extruder with standard knife equipment, the composition having a minimum of about 40 wt % meat content. Generally the minimum of cellulosic fiber is about 5 or 6 wt % of the diet composition, desirably a minimum of about 7, 8 or 9 wt %. The maximum quantity of cellulosic fiber is the amount compatible with the diet, palatable to the mammal, generally dog or cat, and consistent with the nutritional needs and components of the remainder of the diet. Generally, the maximum does not exceed about 25 wt % of the diet and generally not more than about 20 wt % of the diet.
The invention process is advantageous because ordinary extruder equipment can be employed. Lengthier than usual extruder barrel for retexturization to coagulate protein generally followed by longer land length than normal dies to cool the extrudate are not necessary. Example(s) of such ordinary extruders include commercially manufactured single screw extruders, twin screw extruders such as a Wenger TS-52 twin screw extruders system, Clexpral Bc45 V, Wenger TS-52 twin screw extruders, and the like.
Dry diets, generally those having not more than about 30 wt % water are readily prepared through the inventive process. Such a process prepares an essentially homogeneous strand which is cut by a standard knife. Examples of such knives include rotating die face knife, rotating drum knife, and guillotine knife. This is in contrast to the wet diets of the xe2x80x9cchunk and gravyxe2x80x9d type where the meat is in discrete xe2x80x9cchunksxe2x80x9d and post extruder with standard knife equipment, the composition having a minimum of about 40 wt % meat content. Generally the minimum of cellulosic fiber is about 5 or 6 wt % of the diet composition, desirably a minimum of about 7, 8 or 9 wt %. The maximum quantity of cellulosic fiber is the amount compatible with the diet, palatable to the mammal, generally dog or cat, and consistent with the nutritional needs and components of the remainder of the diet. Generally, the maximum does not exceed about 25 wt % of the diet and generally not more than about 20 wt % of the diet.
The invention process is advantageous because ordinary extruder equipment can be employed. Lengthier than usual extruder barrel for retexturization to coagulate protein generally followed by longer land length than normal dies to cool the extrudate are not necessary. Example(s) of such ordinary extruders include commercially manufactured single screw extruders, twin screw extruders such as a Wenger TS-52 twin screw extruders system, Clexpral Bc45 V, Wenger TS-52 twin screw extruders, and the like. Dry diets, generally those having not more than about 30 wt % water are readily prepared through the inventive process. Such a process prepares an essentially homogeneous strand which is cut by a standard knife. Examples of such knives include rotating die face knife, rotating drum knife, and guillotine knife. This is in contrast to the wet diets of the xe2x80x9cchunk and gravyxe2x80x9d type where the meat is in discrete xe2x80x9cchunksxe2x80x9d and deployed in a thickened liquid xe2x80x9cgravyxe2x80x9d. Generally the latter wet diet has at least about 35-40 wt % water content.
The chunks of a wet diet can be produced by the method of this invention. Such method has the additional advantage of obviating the usual equipment necessary to make a xe2x80x9cchunkxe2x80x9d. As used herein the term xe2x80x9cchunkxe2x80x9d is used with respect to any type of meaty particle which is presented to the pet in a discrete form in a gravy type liquid. Such pet food compositions would include chunk and gravy diets, slices that are somewhat elongated, flat discrete particles which have a high percentage of meat, jerky and the like. The process of the invention is now further described.
In general, using a regular extruder such as a Wenger X20 single screw extruderxe2x80x94a meat protein source and a grain mix with vitamins and minerals are incorporated into a preconditioner of the extruder to provide mixing and preconditioning (for example, to slightly steam and moisturize) the formulated meat emulsion. The extruder barrels and screw therein then further mix, heat, coagulate, expand and shear the formulated meat emulsion into meat-like mass which is then formed with different types of die plates for different shape and cut by standard knives for different thickness at the extruder exit.
A raw meat protein source such as beef trim is a meat mix made from either fresh or thawed out frozen meat blocks such as meat or meat by-products. Meat materials can be animal protein muscle or skeletal meats of mammals, fish, poultry or meat by-products such as hearts, livers, lungs, spleen, tongue and the like. The meat protein source is ground through a small grind-plate generally about xe2x85x9 inch and then emulsified to reduce particle size and bone fragments. Sometimes, fat is added as oil or tallow depending on nutrient requirements. The meat protein source is then heated to about 28xc2x0 C. The meat protein source preferably comprises about 25 to 30% protein with a moisture content ranging from 35 to about 42% moisture by weight and the fat content about 8 to about 12%.
A grain mix with vitamins and minerals comprises proteinaceous materials (for example wheat gluten, soy protein concentrate, dry blood plasma), dry carbohydrate materials (for example potato starch, cellulose or cellulose-like materials), salt, spices, seasonings, vitamins, minerals, flavorants, colorants and the like. The amount of this additive mixture depends on the nutritional requirements for different life stages of an animal based on Association of American Feed Control Official""s AAFCO regulations.
These two main components are indexed into the preconditioner at a rate ranging from about 40 to about 52% of the meat protein source, preferably at about 48%. A sufficient amount of steam is injected into the preconditioner to moisten and warm the formulated meat emulsion to facilitate blending with the grain mix. The amount of steam injected is 3-10% by weight of total extruder throughput.
The formulated meat emulsion then enters the extruder which runs at a barrel rpm of about 200 to 450 with an extruder load of about 25 to about 60% of total capacity of the extruder. At such conditions, the meat emulsion is being further mixed, heat coagulated, expanded and sheared to simulate a meat-like texture which can be dependent on the temperature of extruder barrels.
Eventually the extrudate is pressed through a die plate which will give a cross section shape to the strand and then cut by knives at a specific speed for a desired length.
Depending on the varieties of pet food to be made, the extrudate can be formed to make beef jerky type treats, or formed to make high meat dry kibbles or high meat inclusion chunks. These extruded pieces are then allowed to be cooled or dried to different moisture levels. If desired the collected chunks are simply transferred to a canning operation to be filled into cans along with a gravy or sauce to make chunks and gravy products for pet foods.
Below are examples of the invention. These examples are intended to illustrate the broad nature of the invention concept and not unduly limit the invention.